1. SJ has said that some of the iron-rich spheres found in the WTC dust are hollow. This is very significant because it is a common observation in metallic spheres formed in so-called BOF dust produced by a Bessemer converter in a steelworks. In BOF dust it is generally found that small iron spheres are solid while large ones are hollow. This is explained as follows: Molten iron droplets that are expelled from a Bessemer converter are generally high in dissolved carbon that lowers the melting temperature of the material. For example, the iron-carbon phase diagram shows that iron with 4 % C melts at 1147 deg C, thus the presence of carbon helps to keep the droplets liquid. In this state, the droplets rapidly dissolve oxygen that reacts with the carbon to form carbon monoxide, CO. Nevertheless, small iron droplets have a relatively high surface/volume ratio leading to solidification that is so rapid that no gas can form inside the particle. On the other hand, for large droplets where the outer shell solidifies first, the concentration of dissolved carbon and oxygen in the liquid iron is such that carbon monoxide forms, causing the droplet to expand, and the gas to become trapped as the sphere solidifies. (Source: Prof. Neuschutz, RWTH Aachen, Germany)

2. On the question of fly ash in WTC concrete, it is interesting to look at the USGS Particle Atlas that has the EDX spectra for 16 concrete particles identified in WTC dust. Seven of the spectra have no iron at all, while another 4 show very low iron. I believe that the iron in WTC concrete is typically less than 2 wt %. This implies that iron from concrete is no more that 20 % of 2 % or 0.4 % while the USGS reports the total iron in WTC dust to average 1.6 %

3. On the question of sulfiding of steel, there appears to be the common misconception that this can only be caused by ELEMENTAL sulfur. This is simply not true! In fact, if you search the literature on sulfiding of steel you will find it is inevitably attributed to reactions of iron with SO2, SO3 or H2S. Even if we are talking about thermate, which has added sulfur, the violent OXIDIZING reaction on aluminum also oxidizes the sulfur to SO2 which then attacks any iron present forming an iron sulfide-iron oxide eutectic. (Source: Flatley and Birks, Journal of the Iron and Steel Institute, July 1971)

4. Finally, Jones’ new paper makes essentially only two points/observations:

(i) The jet fuel and subsequent office fires in the WTC would have generated temperatures that were generally below say 1100 deg C.

(ii) The presence of spherical iron-rich METALLIC spheres in the size range 50 microns to 1.5 mm in the WTC dust shows that the dust contains particles that were formed at temperatures close to the melting point of iron or 1500 deg C, which is well ABOVE any temperature found in fires from the combustion of jet fuel or materials such as paper, wood, textiles or plastics.

If we accept the validity of both of these observations, the most logical conclusion, but one Jones is apparently loathe to make, is that the iron-rich particles were NOT produced in the WTC fires, (because the fires weren’t hot enough!), but were already present in these buildings prior to 9/11. Jones must therefore show that the WTC microspheres were NOT from a long list of possible candidates, (e,g. welding fumes, wear particles, etc), that were probably already in the towers pre-9/11 before he starts suggesting any nefarious source(s) of these spheres. (Which I admit he hasn't done in his new paper, but he did do in his Boston presentation).

This means Jones must provide QUANTITATIVE DATA on the % of microspheres in his samples as well as the total iron. Without this information we really don't have much to talk about on Jones' latest missive.